unnoticeably

/ʌnˈnoʊtɪsəbli/
adverb
  1. In a way that is not easily seen, heard, or detected; without attracting attention.
    • The cat moved unnoticeably through the tall grass, stalking its prey.
    • The color of the paint faded unnoticeably over many years of sunlight exposure.
    • She slipped unnoticeably out of the meeting while everyone was focused on the presentation.
Antonyms
What does "unnoticeably" mean? | whatsthatwordmean | whatsthatwordmean